Heat and mass transfer during cooling and storage of agricultural products as influenced by natural convection

<p/>Three different models of bulk-stored agricultural products with air flow through the bulk, predicting the temperature profiles or the velocity of natural convection, are developed. The temperature distribution in a cylindrical container with insulated walls and open top and bottom, filled with heat-generating model material is studied experimentally, used to calculate the velocity of natural convection and compared with model predictions. A two-dimensional two-phase model of temperature and moisture distribution during cooling and storage of agricultural products in a cylindrical container is developed. The influence of convective transport (natural and forced convection), heat generation, heat conduction, evaporation, condensation and moisture diffusion is incorporated in the model equations. A sensitivity analyses with this model is presented. The model calculations are compared with the measured temperature course during self-heating of potatoes or model material. Three-dimensional natural convection in a closed container filled with heat-generating products is modelled with a three-dimensional one-phase model. Temperature measurements in a rectangular container filled with model material, potatoes or Brussels sprouts are discussed and compared with the model calculations. Literature on natural convection in porous media with or without heat generation and on models of bulk-stored agricultural products is reviewed.